Southwest Airlines has issued an update to its iPhone and iPod touch app that should make the lives of several frequent travelers a bit easier. The company has added mobile boarding pass support to the app for 28 airports, which is up from the previously supported handful of airpots. Here are all the supported airports (including the new 28 and previously supported ones):

ABQ, ATL, AUS, BWI, BNA, BUR, DAL, DEN, FLL, HOU, LAS, LAX, MCI, MCO, MDW, MKE, MSY, OAK, PHL, PHX, RSW, SAN, SFO, SJC, SMF, SNA, STL, TPA

Mobile boarding pass functionality allows travelers to pull up their pass on their phones to be scanned upon check-in and security checkpoints at airports. Some additional features to make the user-interface simpler and more helpful have also been added in this 2.4 update:

-New upcoming trip cards on your homepage so you can quickly view the info that matters to you the most while traveling like Flight Status, Boarding Position, and Gate Information. -Ability to access our most popular tools like Checkin and your Mobile Boarding Pass options right from the home screen. -Additional bug fixes and improvements.

The update is (of course) free on the App Store.